Water tube boiler of the yarrow type



se ta, 1932.

H. E. YARROW WATER TUBE BOILER THE YARROW TYPE 2 Sheets-Sheet 1 Filed March 28, 1-929 flvzzzfor )[graZgICZ29arraza Sgpt. 6, 1932. H, E, mow 1,875,792

WATER TUBE BOILER OF THE YARROW TYPE Filed March 28, 1929 2 Sheets-Sheet 2 /7 Vania/r fig/old 4 raw I Ea/77 91.

Patented Sept. 6, 1932 UNITED STATES nmom) EDGAR YARROW WATER TUBE BOILER Application filed March 28, 1929, Serial No This invention relates to water tube boilers of the Yarrow type having two elevated steam drums and consists in an improved construction of such boilers which has for its principal object to provide a boiler of large capacity, while retaining the advantages, inherent in the Yarrow type of boiler, which results from the provision of nests of steam generating tubes ateach side of the furnace.

It has been proposed in water tube boilers having two steam drums each connected with a parallel water drum on the same side of the furnace by an inclined bank of water tubes, transversely traversed by the furnace gases on their way to the uptake, to provide crossconnecting tubes adjacent to the combustion space between each water drum and the steam drum on theopposite side of the furnace to two steam drums have a pitch in the longitudinal direction of the steam and water drums very considerably greater than the pitch of the other steam generating tubes connecting the water drums with the steam drums, there-- by precluding birdnesting, while still effectively screening the parts of the steam drums which would otherwise be exposed to .direct radiation from the furnace. Moreover, as the cross-connecting tubes keep the spaces behind them relatively cool, birdnesting is also prevented in the inclined banks of steam generating tubes in rear of the cross-connecting tubes.

The invention is illustrated in the accompanying drawlngs, wherein Fig. 1 shows in cross section the parts of a Yarrow type of boiler essential to the understanding ofthe invention, Fig. 2 is a cross section on line 22 of Fig. 1, and Fig. 3 is a view similar to Fig.

1 showing a modification. .It is to be understood that any system of firing may be used. As therein shown, there are provided two steam drums A, A the steam spaces of which are connected by crosstubes B and the water balance the pressure in the said steam drums.

, or QCOTSTOUE 'SCO'fLAND boilerfurnace there are two water'drums D, E and D, respectively, and thesfe water drums are'connected' 'wit h the steam drum; on the respective sides bymeaiisof nests of'generating tubes F, G and F','G respectively. As-shown in the drawings, the nests of tubes F,F are of considerably greater; depth than the nests G, G',and;the-water drums D, D are of correspondingly greater "diameter." Further, the water drum E isQ'cros's-connected with the steam drum A by one or' more .rows of tubes H' and similarly the-water drum 1 i's cross-connected with" the steam drum A by one or more rows of tubes H; 'These tubes 'may' be straight, as shown in full lines the" drawingsyorthey'inay be curved as shown in 3, thel'atter arrangement being preferred, so as fto-securefas large a combustio'n chamberas'p0ssible. i I 1 In Yarrow boilers the tubes are usually pitched as closely togetherfas Ipossible consistent with ensuring adequate strength of the steam and watendrumsi Thus, in the boiler illustrated the tubes F, F, G, G are closely pitched in the usual manner, but the preventing what is'known as bird-nesting, that is to say such an accumulation of a deposit of slag, ash or soot on the'tubes as to bridge across the space between adjacent tubes in a row. For this reason the pitch of a the tubes H, H in the longitudinal direction is made twice that, for example, of the tubes G, G. As, however, the two sets of tubes H, v H interlace with each other in crossing, the parts of the steam drums A, A which would otherwise beexposed to direct radiation, are still efl'ectively screened therefrom. F urthermore, as the tubes H, H keep the spaces behind them relatively cool there is for this reason less liability of bird-nesting to occur between the tubes such as G, G in rear of tubes H, H. i

Between the two nests of tubesF, G and also between the tubes F, G there may be interposed a superheater or re-heater of any spaces'by cross tubes C. On each side of the convenient construction. These are indicated at I and I respectively.

The furnace gases divide towards the right and left, passing amongst the several groups of tubes on'either side and around the outsides of the steam drums to the uptake;

Having thus described the nature of the said invention and the best means I know of carrying the same into practical effect, I claim A water tube boiler of theYarrow' type,

comprising two parallel steam drums and a plurality of water drums on each side of the furnace and parallel with the said steam drums, inclined banks of steam generatin tubes connecting the wateridrums ateac side of the furnace with the steam drum on that side and a plurality of rows of steam generating tubes on both. sides of and immediately adjacent to the combustion space and directly connecting the innermost water drum oneach side'of'the furnace with the steam drum on the oppositeside of the furnace, the tubes of each row of said plurality of rows ofv steam generating tubes registering, respectively, with tubes of the adjacent-row transversely of said steam and water drums and being spaced apart'longitudinally of said steam and water drums approximately twice the distance between adjacent tubes of said banks of steam generating tubes to preclude bird-nesting, while still. effectively screening the parts of the steam drums which would otherwise be exposed-to directradiation from the furnace as well as balancing the pressure in the said steamdrums. l V

In testimony whereof I have signed my name to this specification.

r HAROLD E. YARROW. 

